1. Field of the Invention
The present invention relates to an optical material. More specifically, the invention relates to a resin composition for sealing an optical device such as an LED element that exhibits high levels of heat resistance and ultraviolet light resistance, as well as excellent optical transparency and favorable toughness, and also relates to a cured product obtained by curing the composition, and a method of sealing a semiconductor element that uses the composition.
2. Description of the Prior Art
Because of their favorable workability and ease of handling, high transparency epoxy resins and silicone resins are widely used as the sealing materials for optical devices such as LED elements. Recently, LEDs with shorter wavelengths such as blue LEDs and ultraviolet LEDs have been developed, and the potential applications for these short wavelength LEDs are expanding rapidly. Under these circumstances, conventional epoxy resins and silicone resins suffer from various problems, including yellowing of the resin under strong ultraviolet light, or even rupture of the resin skeleton in severe cases, meaning the use of such resins in these applications is problematic. In the case of ultraviolet LED applications, sealing with resins is particularly problematic, meaning sealing with glass is currently the only viable option.
Accordingly, the development of a resin composition which not only retains the excellent levels of heat resistance, toughness and adhesion required of a sealing material, but also resolves the problems described above by exhibiting excellent levels of optical transparency and ultraviolet light resistance, has been keenly anticipated.